Anastomosis, the surgical formation of a passage between two normally distinct organs or spaces, is a critical part of many surgical procedures. This is particularly true for coronary artery bypass graft (CABG) procedures in which one or more graft vessels are joined to coronary arteries. The distal end of the graft vessel is typically joined to the coronary artery distal to the stenosed or blocked portion of that artery, in order to improve the blood supply to the myocardium. The graft vessels normally used include the saphenous vein of the leg and the radial artery of the arm. After the graft vessels are harvested, they are cut to the correct length, and then joined on their proximal ends to a blood supply vessel, usually to the aorta. Thereafter, the distal end of the graft is attached to the coronary artery. In an alternative procedure, the internal mammary artery (IMA) is used as a graft vessel. In this procedure the artery is temporarily clamped, severed at a location allowing enough length to be redirected towards the heart, dissected from the chest wall and arterial side branches, and then the distal end (pedicle) is attached to the lower anterior descending coronary artery (LAD) to improve or restore blood flow to the myocardium of the heart. In this case, the anastomosis (the suture attachment) is made only at the distal end, or pedicle, of the IMA.
For the grafting procedures mentioned above, the type of vascular anastomosis used is typically referred to as an end-to-side type. That is, the open end of the graft vessel is attached to the side of the target vessel. However, other types of anastomosis are used as well. The end-to-end type of anastomosis is common for joining together larger hollow organs such as bowel, but can also be used for heart bypass procedures, especially for cases where the arterial flow is completely occluded by the stenosis in the diseased artery.
Some surgeons choose to complete all the proximal anastomoses to the aorta before commencing the distal anastomoses to the coronary arteries. In contrast, others choose to complete the distal anastomoses first. Regardless of the order, when undertaking the distal anastomoses to the coronary artery, it is important that the vessel graft be held steady and adjacent the coronary artery, with a minimum of vascular trauma and a minimum of visual and surgical obstruction by instruments in the narrow operative field.
Currently vascular anastomosis is accomplished by hand suturing with a tiny, curved needle and very fine suture filament. The suturing method, however, is very time consuming and requires several minutes per anastomosis, even for an experienced surgeon. In some cases the blood flow in the newly joined vessels may be poor, and the surgeon must remove the stitches and repeat the suturing procedure. In surgical procedures involving multiple bypass grafts, the time accumulated for doing the suturing is very substantial, putting the patient at risk and increasing the cost of the surgical procedure.
Hand suturing also requires a high level of skill and is not easily mastered by many surgeons. The preferred type of suturing method for the anastomosis of blood vessels is where the needle is passed through the wall of the first vessel (such as the coronary artery) from the inside to the outside, and then passed from the outside to the inside of the second vessel (such as the graft vessel), so that when the suture is drawn tight, the inside walls of the vessel come together, intima-to-intima. This is to insure that the vessels heal together properly with a smooth layer of endothelial cells formed on the inside of the anastomosis. A single stitch would first be done in this manner at each of the heel and toe locations of the anastomosis, and then a running stitch, or a series of interrupted stitches, would be made on each half of the anastomosis between the heel and toe locations.
It is especially difficult to suture if the anastomosis site is not easily accessed or viewed. For the standard CABG procedure, access to the heart is obtained via a median sternotomy in which the rib cage is split longitudinally on the midline of the chest, and the left and right rib cages are spread apart. Less traumatic means of access are becoming more widely used in recent years, including a cardiac procedure known as MIDCAB (Minimally Invasive Direct Coronary Artery Bypass). In one version of a MIDCAB, access to the heart is obtained by using a small, left thoracotomy (incision between the ribs on the left chest) directly above the heart. In this procedure, the surgeon's access to the heart and visibility of it are significantly reduced, and hand suturing is even more difficult than when using a median sternotomy. Other new developments in the surgical procedures have made conventional suturing even more difficult. More and more surgeons are operating on a beating heart to avoid the complications associated with using a heart lung bypass machine.
A number of devices for augmentation of the suturing techniques have been developed. These devices attempt with varying degrees of success to reduce the difficulty in repeatedly passing a needle and thread through the vascular walls. Recent examples are found in U.S. Pat. No. 5,571,090 issued to Sherts on Nov. 5, 1996 and U.S. Pat. No. 5,545,148 issued to Wurster on Aug. 13, 1996. In both Sherts and Wurster, the devices described are for facilitating the passing of the needle through the tissue. Individual stitches, however, must still be made one at a time, and therefore, the anastomosis procedure is still time consuming and tedious. This is because a significant portion of the time required for suturing together very small blood vessels is spent on properly capturing a margin of tissue to be penetrated with the needle, and then placing the needle at precisely the correct distance from the edge of the incision and from the adjacent stitch.
Another variety of devices well known in the surgical art are known as purse string devices. They incorporate a method for holding a severed end of a tubular organ between two clamping implements and providing passages through these implements in order to guide a needle and an attached suture filament. Then several stitches can be made at once with the stitches being precisely spaced apart. The clamping surfaces of the implements contain interlocking teeth or undulations so that the tissue assumes a serpentine shape when thus clamped. The suture filament is sewn into the organ so that its lumen can be drawn closed by pulling on the ends of the suture filament. Some examples of these devices are described in U.S. Pat. No. 4,915,107 issued to Rebuffat, et al, on Apr. 10, 1990, U.S. Pat. No. 5,188,636 issued to Fedotov on Feb. 23, 1993, and U.S. Pat. No. 5,411,481 issued to Allen, et al, on May 2, 1995. These devices were described for use on large tubular organs such as bowel, and they were each intended for applying the purse string suture to the severed end of one organ. This type of suturing technique is commonly used in combination with surgical, circular staplers for the anastomosis of large hollow organs such as the small and large intestines. The purse string suture is used to draw down the lumen of the hollow organ around a shaft of the stapling instrument prior to stapling. In all of these examples for purse string devices, the tissue wall of the hollow organ to be sutured is held by the device so as to have a serpentine shape in the longitudinal direction. A straight needle is then passed manually through the "peaks" of the indulations.
Another device which is somewhat similar to the purse string devices is described in U.S. Pat. No. 3,019,789 issued to Whitehill, et al, on Jun. 30, 1958, and is described for use in the side-to-side anastomosis of blood vessels. The device described requires that an incision be made in each of the blood vessels to be joined. The device has two, slender clamping implements with mating, serpentine, clamping surfaces. Each implement is inserted into the incision of the respective blood vessel, then the implements are brought together and locked, thus holding the vessels side by side with the compressed vessel walls taking on the serpentine shape. Longitudinal holes in the implements are used to guide straight needles so as to join the two vessels together with the suture filaments. A longitudinal slot between the needle holes is provided so that a knife can be pushed through the length of the implements in a manner which results in the creation of a passage between the vessels. The device is then removed and the ends of the suture filaments are finally tied together. A drawback of this device is that the purse string type of stitches created in the joined vessels is not the type described earlier which is preferred by surgeons for creating an anastomosis. A further drawback is that the device is described only for use in a side-to-side anastomosis. As noted earlier, the type of anastomosis required most often for coronary artery bypass procedures is of the end-to-side type. Perhaps the most significant drawback, however, in light of the new surgical procedures being developed, is the need to put the clamping arms of the device inside the lumens of the vessels to be joined. This precludes the ability to anastomose vessels while blood flow is maintained within them, and also greatly limits the size range of vessels which can be joined together with the device.
For any surgical device used for vascular anastomosis, it is extremely important that both the graft and the target vessel not be manipulated to the extent that significant trauma to the vessels occurs. Again, this is to insure that the vessels heal together properly and a smooth passage between them is created. Current methods of vascular anastomosis of a graft to the coronary artery require that blood flow be temporarily stopped using some kind of clamping device on each vessel proximal to the anastomosis site. These clamping devices can risk injury to the artery, thus comprising the long term viability of the vessel to maintain blood flow.
Because of the aforementioned considerations, there is a need to provide a surgical device for facilitating the placement of sutures for the side-to-side or end-to-side types of anastomosis of very small hollow organs such as blood vessels. There is a need that the device require minimal manipulation of the blood vessels and that the resulting anastomosis be non-leaking. There is a need that such a surgical device not introduce structures within the blood vessels which may unduly damage the delicate interior lining of the vessels, and that the inside, endothelial lining of the vessels be permitted to heal rapidly. Furthermore, there is a need for the surgical device to facilitate the anastomosis of the blood vessels while blood flow through the target vessel is maintained. Finally, there is a need that the device be adaptable to use in traditional, open cardiac procedures (CABG) as well as in less invasive procedures such as MIDCAB.